1. Field of the Invention
The present invention relates generally to stereotactic breast biopsy systems and more particularly to a needle guide suitable for use in a stereotactic breast biopsy system to guide insertion of a biopsy needle into a patient.
2. Description of the Related Art
Stereotactic breast biopsy systems are a precise, minimally invasive diagnostic tool for use in performing fine-needle aspiration and needle core biopsies of the human breast to determine whether a breast lesion is benign or malignant. Needle biopsies, unlike more invasive surgical procedures, are typically performed on an out-patient basis with local anesthesia. Stereotactic breast biopsy systems generally include an ergonomically contoured table that comfortably supports the patient in a stable, fixed position that exposes the patient's breast. Stereotactic breast biopsy systems also generally include a diagnostic imaging system for targeting the lesion to be biopsied. The location of the target lesion is used by a guidance system to guide insertion of the biopsy needle into the patient's breast tissue.
The biopsy needle used in a stereotactic breast biopsy is typically a component of a biopsy gun, which is supported by the guidance system in an appropriate holder. The biopsy needle is relatively long requiring the holder to include a support bracket to reduce deflection of the biopsy needle during deployment and use. The support bracket typically includes a needle guide at a distal end thereof through which the biopsy needle passes. The needle guide minimizes non-axial movement or deflection of the biopsy needle during a biopsy to ensure that the biopsy needle is inserted into the correct location of the patient's breast adjacent the target lesion.
Typical biopsy needle guides include an upper support portion having a hole through which the biopsy needle extends and a lower attachment portion that is removably secured to a cylindrical pin on the support bracket. The lower attachment portion of the biopsy needle guide includes a pair of spaced apart, downwardly extending legs that define a generally circle-shaped void therebetween to accommodate the diameter of the support bracket pin once the components are secured together. Because the support bracket pin is larger than the space between the needle guide legs, the legs are deflectable laterally away from each other as the biopsy needle guide is assembled vertically onto the pin.
During operation of the stereotactic breast biopsy system described above, the biopsy gun is first placed in the appropriate holder. The coordinates of the lesion, as determined by the diagnostic imaging system, are dialed in and the needle tip is moved forward until the desired pre-deployment position of the holder is achieved. The holder and biopsy gun are then deployed causing the biopsy needle to be inserted into the patient's breast tissue. The deployment of the biopsy needle into the breast is typically instantaneous, as the biopsy gun holder is generally spring loaded or otherwise configured for rapid deployment.
Due to the density of the breast tissue, the forces imposed on the biopsy needle guide are not necessarily axial, i.e., along the axis of the biopsy needle. More particularly, the forces imposed on the needle guide are primary axial with a component of the force being perpendicular to the axis of the biopsy needle due to deflection of the biopsy needle entering the relatively dense breast tissue. In other words, a component of the deployment force is imposed on the needle guide in the vertical direction. When the vertical force imposed on the needle guide exceeds the resilient force of the needle guide legs around the support bracket pin, the needle guide can move relative to the support bracket, or becomes disengaged therefrom. The limitations specifically minimized and/or eliminated by the present invention include improper deployment of a biopsy needle due to movement of the biopsy needle guide relative to the support bracket.